Washington State Attorney General Bob Ferguson plans to file a lawsuit in federal court against President Donald Trump over an executive order that bars refugees and limits immigration from seven countries with majority-Muslim populations.

What to know about Washington state's lawsuit

Ferguson announced his lawsuit Monday, becoming the first state attorney general to announce legal action against the Trump administration over one of its policies.

Ferguson's complaint asks the United States District Court for the Western District of Washington to declare key provisions of the executive order unconstitutional and illegal.

He also filed a motion for temporary restraining order seeking an immediate halt to the executive order's implementation.

>>Related: Trump immigration ban causes fear anger among Muslims, politicians

The complaint says that the president's actions are "separating Washington families, harming thousands of Washington residents, damaging Washington's economy, hurting Washington-based companies, and undermining Washington's sovereign interest in remaining a welcoming place for immigrants and refugees."

Ferguson asked the court to schedule a hearing within 14 days.

Major Washington state institutions supported the lawsuit through declarations filed alongside the complaint. In their declarations, Amazon and Expedia outlined the negative ways the executive order affects their operations and their employees.

What is the 'immigration ban?'

Any non-U.S. citizen from Iraq, Syria, Iran, Sudan, Libya, Somalia or Yemen is now barred from entering the United States.

Legal permanent residents -- green card and visa-holders -- from those seven countries who were out of the United States after Friday cannot return to the U.S. for 90 days.

The order also singled out Syrians for the most aggressive ban, indefinitely blocking entry for anyone from that country, including those fleeing civil war.

>>Related: How Syrian refugees get to come to America

The order also directed U.S. officials to review information as needed to fully vet foreigners asking to come to the U.S. and draft a list of countries that don't provide that information. That left open the possibility that citizens of other countries could also face a travel ban.

The immediate fallout from Trump's order meant that an untold number of foreign-born U.S. residents now traveling outside the U.S. could be stuck overseas for at least 90 days — despite holding permanent residency "green cards" or other visas.

Individuals detained at Sea-Tac Airport

Travelers across the nation were detained at airports. Critics described widespread confusion with travelers being held in legal limbo because of ill-defined procedures.

On Saturday, individuals were detained at Seattle-Tacoma International Airport as a result of Trump's executive order. They were released by the Department of Homeland Security, a Port of Seattle spokeswoman said Sunday.

About 3,000 protesters holding signs and chanting "no hatred, no fear, immigrants are welcome here" and "let them in" gathered Saturday evening and continued demonstrating into early Sunday morning at Sea-Tac airport.

The crowd dispersed shortly after midnight, but about 30 to 35 were arrested during the demonstration and face various misdemeanor charges. She said there were no injuries or damage to the facilities.

All but one person was cited and released for disorderly conduct. That one person was arrested for assault, according to officials.

Large protest gathers at Westlake, across nation

Trump's order ignited nationwide protests throughout the weekend.

In addition to the Sea-Tac protest, thousands of people are attending an "emergency rally" Sunday night at Westlake Park in response to President Donald Trump's executive order on immigration.

>> Related: Protests erupt in response to Trump's executive order on immigration

Gov. Jay Inslee and Mayor Ed Murray were among the speakers at the large rally.

Murray urged protesters in the city to stand in their doorways at 7 p.m. Wednesday evening, holding a phone or a candle to "shine a light."

"We as a city will stand with immigrants and refugees," said Murray, who has vowed to maintain Seattle's status as a sanctuary city for immigrants despite a Trump threat to withhold federal funds.

Protesters marched through downtown streets after the rally.

ACLU filed first lawsuit challenging EO

The American Civil Liberties Union filed the first lawsuit challenging the executive order.

>> Related: Trump administration in defense mode over controversial Muslim travel ban

"We're arguing that the executive order is unconstitutional. And that it's unlawful. The merits of that will be fully broached in coming weeks," said ACLU executive director Anthony Romero.

Four federal judges have put various holds on the ban, and other courts are expected to consider similar stays.

Supporters of ban

The top Senate Republican, majority leader Mitch McConnell, avoided directly criticizing the president and said the courts would have to decide the legality of the president's actions.

Trump's advisor, Stephen Miller, defended the ban.

On "CBS This Morning," he said all seven countries named were identified by then-President Barack Obama's administration as "countries of concern," but the administration did nothing to protect our borders.

>> Related: Donald Trump blames airport woes on 'tears of Sen. Schumer,' computer glitches, protesters

"They left our borders fairly open and there were unfortunate deaths because of that, including sanctuary cities and non-enforcement of removal orders," said Miller.

House Speaker Paul Ryan also agreed with Trump's ban.

"President Trump is right to make sure we are doing everything possible to know exactly who is entering our country," said Ryan.

The president responded to criticism Monday on Twitter, saying only 109 people were detained and questioned.